From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id DF6BB35E1CE for ; Tue, 23 Jun 2026 09:24:17 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782206658; cv=none; b=YM1lre5DzJvtWhAH/igBNf1v+gvCwfwM/nWovL4/foSy4y16+eSG998dSYjsD0PZlSQC+4+kg/0ZajlD/riZwuFVzndxMTsVz8qmGIR8Ruq3uI5TJANpjCxNB6Wk/2KL1i2PyFv6cn5CptoxSBMRC/3CG4Dn/33tK5bouO9yOOg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782206658; c=relaxed/simple; bh=G/sS+eV/En7VfNNCxb94MAg33YSpnby1kQ+wnVsYp2o=; h=From:Subject:To:Cc:In-Reply-To:References:Content-Type:Date: Message-Id; b=kHYNiW+FrCwNtq/C4B9al0KvhDePG0z+H+rCGpjA3zPzZnfPDUtzHjeE4Db/it9CtYuNuCC6Zee6IyOsh0qzjEy4XShg188vCi2UYiSg2guMH6rmwozCVUsAdMFjYe6/Ufac38QyBSZdAAuEqD4cq7PCNRPO+/54kEI/zew88N4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=J7ysAWyd; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="J7ysAWyd" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5964D1F000E9; Tue, 23 Jun 2026 09:24:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1782206657; bh=uu1gE+w0IIygPtSqc3DOpPTSEN1y4A9sZQObYVtvI0c=; h=From:Subject:Reply-To:To:Cc:In-Reply-To:References:Date; b=J7ysAWydymKcjf6Skd5/xkKIIEQ2M3RHxmxoHqRs9fWuNZ4aAwMHr8/KwMWbaXILz zF4Ff25gsnknGSgGzJ0TOjd3NC6HE2T8JaDEj7R1v/C22/w/F8XuLU5x5oM0DPhBBP o9Dw6086kKLzF6qAkeFM9JKAgyhgklxd1SLOvcpjiNH5MXP4J3vcCh/5uzUkGt71dk ZGQzF8XVvcBhuSSGIGpDfa21nqqp6z22a2Wql70GAVbk79ycZYYeM+5JGRtiXyZo75 IuRDWM4NqS7F/1P/enlXu4fiOxAqb9sRMSLJcpq6gdvI0l/IYowlDbxX5WPG9kxSuR Il/xlrThQvPhA== From: sashiko-bot@kernel.org Subject: Re: [PATCH 2/4] kvm: sev: Unmap pages in correct order in sev_gmem_post_populate() Reply-To: sashiko-reviews@lists.linux.dev To: =?utf-8?b?SsO2cmcgUsO2ZGVs?= Cc: kvm@vger.kernel.org In-Reply-To: <20260623091556.1500930-3-joro@8bytes.org> References: <20260623091556.1500930-1-joro@8bytes.org> <20260623091556.1500930-3-joro@8bytes.org> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Date: Tue, 23 Jun 2026 09:24:16 +0000 Message-Id: <20260623092417.5964D1F000E9@smtp.kernel.org> Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Thank you for your contribution! Sashiko AI review found 1 potential issue(= s) to consider: Pre-existing issues: - [High] The patch corrects the `kunmap_local()` LIFO unmapping order in th= e initial setup path but leaves an identical unmapping violation in the CPU= ID firmware error-handling path of `sev_gmem_post_populate()`. -- commit 6fe2af9a226230e3ae153d850afdecbdb7d9f3cc Author: Joerg Roedel kvm: sev: Unmap pages in correct order in sev_gmem_post_populate() This commit corrects the unmapping order of kmap_local() pages in the initial setup path of sev_gmem_post_populate(), ensuring strict LIFO ordering. > diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c > index 41dcba5180cad..f09d15f68964b 100644 > --- a/arch/x86/kvm/svm/sev.c > +++ b/arch/x86/kvm/svm/sev.c > @@ -2360,8 +2360,8 @@ static int sev_gmem_post_populate(struct kvm *kvm, = gfn_t gfn, kvm_pfn_t pfn, > =20 > memcpy(dst_vaddr, src_vaddr, PAGE_SIZE); > =20 > - kunmap_local(src_vaddr); > kunmap_local(dst_vaddr); > + kunmap_local(src_vaddr); > } > =20 > ret =3D rmp_make_private(pfn, gfn << PAGE_SHIFT, PG_LEVEL_4K, [Severity: High] This is a pre-existing issue, but while this hunk fixes the unmapping order in the initial setup path, does the identical LIFO unmapping violation still exist further down in the CPUID firmware error-handling path of sev_gmem_post_populate()? If an untrusted userspace process supplies invalid CPUID data during KVM_SEV_SNP_LAUNCH_UPDATE, the firmware returns SEV_RET_INVALID_PARAM. This directly reaches the error path where src_vaddr and dst_vaddr are mapped, but unmapped out of order: arch/x86/kvm/svm/sev.c:sev_gmem_post_populate() { ... if (ret && !snp_page_reclaim(kvm, pfn) && sev_populate_args->type =3D=3D KVM_SEV_SNP_PAGE_TYPE_CPUID && sev_populate_args->fw_error =3D=3D SEV_RET_INVALID_PARAM) { void *src_vaddr =3D kmap_local_page(src_page); void *dst_vaddr =3D kmap_local_pfn(pfn); memcpy(src_vaddr, dst_vaddr, PAGE_SIZE); kunmap_local(src_vaddr); kunmap_local(dst_vaddr); } ... } Should this second instance be updated to reverse the unmap order as well to prevent kmap stack corruption? --=20 Sashiko AI review =C2=B7 https://sashiko.dev/#/patchset/20260623091556.1500= 930-1-joro@8bytes.org?part=3D2